The present invention relates to a machine for the treatment of products made of plastic material of the recyclable type, for instance bottles or the like and, in particular, a machine that allows such products to be treated in a continuous process.
The products in plastic material containing one or more recyclable parts are generally sent to the recycling plants in different forms, for instance in loose form or as bales or blocks comprising a plurality of compacted products. In the latter case, in order to allow the recovery treatment to be carried out, the compacted blocks must be disgregated for obtaining the separation, or singularization, of each product, as happens for instance in the plants for the recovery of PET from the common bottles use for drinks, mineral waters and the like.
Subsequent to the singularization phase, or simultaneous with it, the bottles are subjected to one or more washing phases with a treatment fluid, possibly heated, for removing the waste materials comprising for example labels made of paper or plastic material fixed to the bottles by means of adhesive or the like.
The only known example relating to a machine which allows the separation of bottles and their simultaneous washing in a continuous way, is disclosed in the European Patent Nr. EP-0558528. Indeed, this document discloses a machine which allows to carry out the disaggregation of the compacted agglomerates of bottles and their simultaneous washing. This is made by means of a combination of the mechanical action of bodies that strike the blocks of compacted bottles and the thermo-hydraulic action of the treatment fluid.
In general, the machine disclosed in the cited European Patent, comprises a hollow cylinder which rotates about a horizontal axis. It is provided an inlet, regulated by means of a suitable valve, through which the bottles are feed in a bulk form, i.e. as compacted aggregates as well as single bottles. It is further provided an outlet, also regulated by a suitable valve, through which the singularized bottles are withdrawn. Inside the cylinder there are provided means for mechanically disaggregating the agglomerates of bottles and means for feeding a treatment fluid at a pre-set temperature.
The inside of the treatment cylinder is divided into chambers, separated by walls equipped with ample central openings, through which the bottles are conveyed successively due to the action of one or more helically arranged blades arranged on the inside wall of the cylinder. In the chambers near the inlet for the bottles, there are floating or suspended bodies which strike the agglomerates of bottles and facilitate the disaggregation of the same.
One of the main characterising aspects of the machine disclosed in the cited European Patent is that the cylinder is provided with a continuous side wall that allows a pre-determined volume of the treatment liquid to be retained inside the cylinder. The excess liquid flows out from the central openings arranged at the opposite extremities of the cylinder.
The machine described in the cited European Patent must have particularly large dimensions, both to guarantee a high working capacity and to keep the bottles inside the rotating cylinder for a sufficiently long time in order to ensure the effectiveness of the washing and separation treatment.
The treatment is therefore carried out by subjecting continuously the bottles, and the agglomerates of the same, to immersion on the treatment liquid. As well as requiring considerable quantities of treatment liquid remaining inside the cylinder, the treatment carried out with this known machine causes inevitably the filling, even only in part, of the bottles with the liquid itself.
This is particularly undesirable, especially by taking into account the fact that the treatment liquid stored in the bottles contains chemical additives or pollutants which may be dispersed during the subsequent steps of the treatment in the environment where the plant is located. Furthermore, the presence of the treatment liquid on the bottles causes a considerable waste of the liquid itself and may interfere with the subsequent phases of transferring and working of the bottles, even only taking into account the increased weight due to the presence of the treatment liquid inside the bottles.
In order to avoid these notable drawbacks, the known plants which comprise a machine such that disclosed in the cited European Patent require a further station, located immediately downstream to the machine, in which it is carried out the emptying of the treatment liquid from the bottles before transferring them to the subsequent working stations.
Furthermore, the presence of separator partitions and the expulsion of the waste materials (labels, stoppers or the like) by means of the treatment liquid that flows out through the central openings arranged to the extremities of the cylinder, makes the same evacuation of such materials difficult and not very efficient. In particular, also in the case of a continuous working process, there must be provided a further screening step in order to allow the complete separation between the bottles and the waste materials.
This being stated, one object of the present invention is to propose a machine of the type specified above, that allows to carry out in a continuous way the disaggregation of the blocks of compacted products, the pre-washing of the products and the ejection of the singularized products at the same time.
Another object of the present invention is to produce a machine of the type specified above which reduces considerably the waste of fluid used during the treatment.
A further object of the present invention is to produce a machine of the type specified above that allows to carry out an effective pre-washing of the products and the evacuation of the majority of the waste materials from the treated plastic products.
Yet another object of the present invention is to produce a machine that allows to treat the products under whatever form, in particular under the form of bales, that is a machine which allows to adapt the treatment of singularization and pre-washing to products independently from the form under which they are fed to the machine, as well as independently from the different characteristics of quality, type and composition.
These purposes are achieved by the present invention, that relates to a machine for the treatment of products made of a plastic material of the recyclable type, in which the products are inserted in the form of blocks consisting of a plurality of compacted products and/or in the form of individual separate products, the machine comprising a drum rotating about one of its own axis, at least one inlet for the introduction of the products to the inside of the drum and means for feeding a treatment fluid to the inside of the drum, characterized in that the drum comprises one or more sections having a perforated side wall and one or more sections having a discontinuous side wall.
This allows to perform in a continuous way and in a single machine three steps of treatment which in the prior art are carried out in three separated stations of the plant. In particular, inside a single machine, it is possible to disaggregate the agglomerates of compacted products, to pre-wash the products and singularize the same.
Also the removal of the waste material, for instance the paper labels which are softened and removed for the majority during the treatment, is made through the sections having a perforated side wall, while the singularized products are expelled one by one in a continuous way from the sections having a discontinuous side wall.
In particular, the drum comprises a first entry section, that is a section located immediately downstream of the product inlet, having a continuous side wall or a perforated side wall. In the first entry section there are preferably provided some radially projecting blades which facilitate the disaggregation of the bales and/or the aggregated products.
According to an advantageous aspect of the invention, it is provided at least a second section, located immediately downstream of the first entry section, having a perforated side wall formed by a plurality of detachable perforated panels. This allows the installation of panels with holes of different diameter depending on the typical dimensions of the waste material to be evacuated from the machine during the treatment of certain products.
It is further provided a third section having a discontinuous side wall, that is a wall formed by detachable rods that are arranged in equidistant relationship in such a way as to form a plurality of exit ports, having substantially equal shape and dimensions, through which pass the singularized products. The rods can thus be arranged depending on the dimensions of the products to be treated by the machine.
The drum also comprises a trailing section, located immediately downstream of the third section, provided with a central opening and one or more vanes arranged on the internal surface. The vanes are oriented in such a way as to cause, during the rotation of the drum, a thrust action towards the third section on at least part of the materials reaching the trailing section. This allows to carry back the products towards the ports provided in the third section of the drum, while the foreign matters having greater dimensions with respect to the products can cross the trailing section in order to be expelled from the machine.
According to another aspect of the invention, all the sections of the drum are arranged so that one continues from the other without separator walls being placed between the same. This allows continuous and effective evacuation of the waste material and guarantees a continuous flow of products towards the section of discontinuous wall, through which the same products leave the machine.
According to another advantageous embodiment of the invention, there are means for varying the angle of inclination of the axis of rotation of the drum with respect to the ground, together with means for regulating the speed of rotation of the same drum. It is possible with this combination to regulate the treatment time of the products, and so adapt the machine to operate with products having different characteristics. A slight inclination allows the products to move towards the section with discontinuous walls, from which the same products escape one by one from the machine.
The drum is located, at least in part, and rotates within a casing. Both the drum and the casing, or at least part of them, are preferably lined with thermo-insulating material, in such a way as to limit the heat loss suffered by the treatment fluid in the case in which a heated fluid is used. In this case, the fluid can be recovered and re-introduced into the machine, thus saving on the consumption of energy necessary to bring it up to the treatment conditions again.
In the lower part of the casing there are a plurality of outlets, of which a first outlet is located in correspondence with the second section of the drum, i.e. that having a perforated side wall, to allow the treatment fluid and waste materials removed from and/or released by the products to flow out; a second outlet is located in correspondence with the third section of the drum, i.e. that having a discontinuous wall, to allow the products to exit one at a time; and a third outlet is arranged downstream of the drum to allow the ejection of foreign matters (for example nets, cardboards or the like) having dimensions greater than those of the products to be treated.
This allows continuous and effective singularization and pre-washing of the products, and the elimination of the waste material.